Violin top concealing dull interior (5)
I believe the answer is:
amati
'violin' is the definition.
(I've seen this in another clue)
'top concealing dull interior' is the wordplay.
I cannot really see how this works, but
'dull' could be 'mat' (mat as opposed to glossy) and 'mat' is found within the answer.
'top' could be 'ai' (resembles A1, term for excellent) and 'ai' is found in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for amati that I've seen before include "fiddler" , "Violin or cello made by a Cremona family" , "Noted violin maker" , "Craftsman" , "family of workers on the fiddle?" .)